Method of and apparatus for controlling the pulp in the pit of a wood-pulp grinder



Aug. 19, 1924. 1,505,758

- J. J. WARREN METHOD OF AND APPARATUS FOR CONTHOLLING THE PULP IN THE PIT OF A WOOD PULP GRINDER Filed March 4. 1924 1 /f L., und f ff man M ATTORNEY/s Patented Alug.19, 1924.

`U,NITED STATES PATENT OFFICE. f

JOHN JAMES WARREN; or'nnowNvILLn, NEW Yonx.

METHOD F AN D APPARATUS FOR CONTROLLING TEE 4IPU'ILE IN THE PIT 0F A.

. WOOD-PULP GRINDEB.

Application led Marchv 4, 1924. Serial No. 696,782.

To all whom 'it may concern:

Be it known that I, JOHN J. WARREN,

a citizen of the United States, residing at Brownville in the county of Jefferson, State' of ew York, have invented certain new and useful Improvements in Methods of and Apparatus for Controllingl the Pulp vin the Pit of a Wood-Pnl vGrrlnder; and I do hereby declare the iollowing to be a full clear, and exact description of the inventlon, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention lrelates to the grinding of wood into the so-called mechanical pul used in the manufacture of newsprint and other cheap papers, and in particular it relates to the control of the pulp in the pit below the grindstone. The present application is a continuation in part of my copending application, Serial No. 594,501, filed October. i4, 1922. f

Immediately below the grindstone, a wood-pulp grinder is usually provided with a pit which first receives the ground pul and in which the lower face of the grind)- stone is submerged. When the pul it flows readily from the it and keeps itself of substantially` uni crm consistency. Wifhen, however, less grinding-water is used and the pulp becomes too think to now easily it often'forms in heavy masses, causing the water to run-away in channels, thus ermittng-the grindstone to become over eated, lwith the possibility of fracturing. Also, small pieces of wood, commonl known as slivers, aresometim'es carried etween the bottom of the cuttingY compartment and the grindstone, and into the pit, where they collect, rubbing against the surface of the stone and burning it, thus destroying its cutting surface. Furthermore, when this condition of the pulp prevails the dry portion of the stone gets filled with dry wood pulp, or what is known as wood flour and cannot clear itself, and .be kept in the proper cutting condition.

It is, however,` advantageous to work with .a thick pulp. A thick ulp is more eiiicient than a thin pulp in c eaning the face of is thin Yin which Fig. 1 is' a transverse vertical secthe stone and keeping it in cutting condition; moreoverz I have discovered that when the pulp is thick, longer andstronger fibers are formed, probably due in part vto the fact that the grinding is performed at a higher emperature which steams and softens the ogs. y

It is, therefore, the object o f this invention to do away so far as possible with the objectionable features commonly attendant u on the use of thick pulp. I do this by p acing an agitator in the pit under the grindstone so as to keep as nearly as racticable lto a very uniform consistency o pulp, and to aid in carrying the mass of thick pulp i under the stone forwardso that a uniform consistency will be presented to the grindstone preventin slivers or thick pulp from divertlng the s ower water and causing it to travel in streaks or around the stone. To accomplish this purpose satisfactorily it is necessary to revolve the entire mass of stock under the stone to a considerable extent, thereby mixing in the water necessary for grinding purposes, and presenting as nearly as possible a uniform pulp to the grinding surface, and Vparticularly to enable the operator to keep a thicker conf sistency in the pit than if operating without an agitator.

In order to control the consistency of the pulp in the'pit, it is custom-ary to add water. It 1s a further object of this invention to provide improved means for doing this. The water, in accordance with the present invention is sprayed 'against a deiecting plate or flash-board depending from the grindstone housing. This plate not only spreads the water but prevents this water, which is quite.y cold compared to the grindstone, from striking the stone and thus possiblyv fracturing it.

A preferred embodiment of the invention is illustrated in the accompanying drawings @s tion through the lowerY end of a magaziney grinder constructed in accordance withythe grinder of my application; and Fig. 2 is a vertical section taken at from the plane of the section of Fig. 1.

' bearings 23.

The grinder shown in these figures comprises the ordinary cylindrical grindstone 21 enclosed within a housing 24e, mounted on a shaft 22, andI journaled in water cooled The f stone is securely iixed upon the shaft'by means of ybushings 25 and concave steel flanges 26. Adjustably mounted on the housing 24 and located centrally over the grindstone is a vertical magazine 29 into the upper end of which is placed the wood to be ground.y This wood is positively and vcontinuously forced against the grindstone by means of a series of endless cha-ins 30, two located on each of the two opposite sides of the magazine parallel with the shaft 22. The operation of these chains has been described in detail in my application and will not be repeated here as itforms no part of the present. invention.

Situated immediately below the grindstone is a pit 27 into which the ground pulp from the stone first passes, and into which the lower face of the stone is partly submerged as shown. To control the depth of the pulp in the pit, I have provided at the discharge side thereof, a swinging dam 28, which may be raised or lowered by any suitable means, thus regulating the position of the overflow.

Situated immediately below the grindstone and within the pulp in the pit, I have provided in accordance with this invention,

anagitator 91. This agitator comprises an endless belt or band of substantially the same width as the pit made up of a series vof straps 103, to which are secured a series of transverse bars or cleats 104, the whole passing about two series of'rollers 105. A shaft 106 upon which one of the series of rollers is mounted, extends through a side Wall of the pit as shown in Fig. 2, and is rotated from the shaft 22 by means of a gear reducer 107. This belt moves the mass of pulp toward the point of discharge and keeps it of uniform consistency even when the pulp is too thick to ow readily itself.

Within the housing and located in front of the grindstone is a spray pipe 82, through which water is added to the pulp in the pit to control its consistency. Depending from the top of the housing and located between the pipe 82 and the grindstone is a swinging flash-board or deflecting late 81, the lower edge of which is serrate or toothed. The water sprayed from the pipe 82 strikes this flash-board and, spreading out, is distributed across the width of the pit. At the same time, this spray is prevented from coming into direct contact with the hot stone and possibly checking or frac-turing it. By making the lower edge of the flash-board serrated or toothed, a better distribution of the added water across the width of the pit is effected.

By the means described above, -I am enabled to obtain a more complete and satisfactory control of the pulp within the pit than has heretofore been possible.

I claim:

1. In a wood-pulp` grinder, the combination of a grindstone, va pit beneath the grindstone for receiving the ground pulp, and means in the plit for agitating the pulp and keeping it of ubstantially uniform consistency.

2. Ina wool-pulp grinder, the combination ofs a grindlstone, a pit beneath the grindstone for receiving the ground pulp, and an endless belt in the pit for agitating the pulp and preventing the accumulation of slivers orlheavy stock, and the formation of channe s.

3. In a wbod-pulp grinder, the combination of a grindstone, a' rotary shaft supporting said grindstone, a pitbeneath the grindstone for receiving the ground pulp, an endless belt i/n the pit for agitating the pulp and preventing the accumulation of slivers or heavy,` stock and the formation of channels, an'yl means for operating the agitator from the grindstone shaft.

4.1m a wood-pulp grinder, the combina tion' ofa grindstone, a pit beneath the grindstone for receiving the ground pulp, and an endless belt in the pit of substantially the /same width as the pit and extending across tit in a substantially horizontal plane for agitating the pulp and preventing the accumulation of slivers or heavy stock, and the formation vof channels.

5. In a wood-pulp grinder, the combination of a grindstone, a pit beneath the grindstone for receiving the ground pulp, and an endless belt in the pit for agitating the pulp and preventing the accumulation of slivers or heavy stock, and the formation of channels, transverse bars or cleats on the belt, and rollers about which the belt passes.

6. In a wood-pulp grinder, the combination of a grindstone, a pit beneath the grindstone for receiving the ground pulp, a spray pipe for introducing additional water to the pulp in the pit, and a Hash-board between the grindstone and the spray pipe for shielding the stone and distributing the water.

7. In a wood-pulp grinder, the combination of a grindstone, a pit beneath the grindstone for receiving the ground pulp, a spray pipe for introducing additional water to the pulp in the pit, and a flash-board between the grindstone and the spray pipe for shielding the stone and distributing the water, the lower end of the flash-board being serrated or toothed.

8. In a wood-pulp grinder, the combination of a grindstone, a pit beneath the grindloisA stone for receiving the ground pulp, a point of discharge. in the pit for the pulp, and

` grinding means within the pit4 for moving the pulp toward the discharge and keeping it of substantially uniform consistency.

9 An improvement in the method of wood pulp by forcing the wood against a rotating grindstone in the presence of water, and passin the pulp'through a pit in which the grinstone runs part y submerged," which comprises reducing the grinding water to a point where the pulp l0 1s too thick to flow readil while positively moving .the thick pulp to the discharge point of the pit and agltatmg it to keep it of uniform consistency.

In testimony whereof I aix my signature.

JOHN JAMES WARREN.- 

